I've owned a classic green flat top, a cople HK SL8's, a coupleACR's, an AR180B, and owned or at least shot a few others like XCR's, T97, mini14.
Out of all of them the HK SL8, ACR and 180 are by far my favorites.
The SA was a high quality and very well made rifle but the accuracy wasn't overly impressive compared to my ACR or HK. To be fair though I only ran AE black box 55gr through it so I'm sure it could have done better. My biggest issue was the poi shift depending how you supported the rifle. Guys will say all non free floated rifles will have a shift but I've never owned a rifle that did it this much.
I ended up sticking with my ACR and AR180 because of the great accuracy and caliber conversion ability of the ACR (made my own conversion kits), and kept the 180 because it's just as accurate as most other black rifles, has decent iron sights and is really lightweight so it's great for packing around.
If I had bought the diopter sight version of the SA I probably would have kept it as I would have used it less off the bench at the range and more in the field where it's accuracy and poi shift would bother me less.
The SA is a great rifle but is a lot of money for something as old as it is and that is very hard to find parts for to personalize it. That said the only thing a SA "needs" is more magazines, as was said earlier the magazines are more reliable and more durable than a STANAG pattern magazine.
I would suggest you find someone with one who will let you run a few mags through it and maybe a few other rifles before you decide.